A turbofan gas turbine engine may be used to power aircraft and may include, for example, a fan section, a compressor section, a combustion section, a turbine section, and an exhaust section. The fan section induces air from the surrounding environment into the engine and accelerates a fraction of the air toward the compressor section. The remaining fraction of air is accelerated into and through a bypass plenum, and out the exhaust section.
The compressor section, which may include a high pressure compressor and a low pressure compressor, raises the pressure of the air it receives from the fan section to a relatively high level. The compressed air then enters the combustion section, where a ring of fuel nozzles injects a steady stream of fuel into a plenum. The injected fuel is ignited to produce high-energy compressed air. The air then flows into and through the turbine section causing turbine blades therein to rotate and generate energy. This energy is used to power the fan and compressor sections. The air exiting the turbine section is exhausted from the engine via the exhaust section, and the energy remaining in the exhaust air aids the thrust generated by the air flowing through the bypass plenum.
In some engines, the compressor section is implemented with a centrifugal compressor. A centrifugal compressor typically includes at least one impeller that is rotationally mounted to a rotor and surrounded by a shroud. When the impeller rotates, it compresses and imparts a velocity component to the air received from the fan section. The shroud directs the air radially outward into a diffuser, which decreases a tangential velocity component and the axial velocity component of the air and increases the static pressure of the air. In this regard, the air is directed around a curved section having a relatively small curvature radius defined by an inner wall and an outer wall of the diffuser. The air is then exhausted out an outlet of the diffuser. The exhausted air then may be directed to a deswirl assembly that includes an annular housing having a plurality of straight radially extending vanes, which are used to straighten and further reduce the axial velocity component of the air flow before it enters the combustion section.
Although the aforementioned configuration operates adequately in most circumstances, it may be improved. In particular, as the demand for smaller engines increases, the dimensions of the engine components, such as diffusers, continues to decrease, accordingly. For example, in some diffusers, the curvature radius of the curved section of the diffuser has been designed to be relatively small. However, the smaller curvature radius may cause airflow around the curved section to have a tendency to separate from the inner wall and to flow toward the outer wall. As a result, the diffuser and engine may not operate as efficiently as desired.
Accordingly, there is a need for diffusion systems and methods that may be implemented into smaller dimensioned engines to optimize engine efficiency. Additionally, there is a need for improved diffusers that may effectively flow air between a centrifugal compressor and an annular deswirl assembly without having to redesign surrounding components. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.